According to criminal charges, he encouraged “naked dance parties,” showed students pornography and held group sex sessions with underage boys.

He pleaded guilty in July.

Also Friday, a Seibel victim filed a lawsuit — the second of its kind — against the private boarding school in Faribault, Minn.

The victim, who attended from 2000 to 2004, is identified as DOE YZ in the suit. The new Minnesota Child Victims Act passed in May eliminated the civil statute of limitations for child sexual abuse survivors and opened a three-year window for prior victims to come forward and hold their abusers and the institutions that may have allowed their abuse accountable in court.

“What’s clear is that Seibel created a culture of coercion, confusion and sexual perversion,” said Doe YZ’s attorney, Jeff Anderson. “What’s just as clear is that many around and at the top of Shattuck-St. Mary’s, wittingly or unwittingly, permitted Seibel’s exploitation of students. We are grateful to all of the survivors who have courageously stepped forward to hold this man and institution accountable for their actions.”

As part of his sentence, Seibel, 71, must register as a sex offender, participate in a treatment program and cannot have access to print or digital materials that are sexually explicit in nature.

In addition to the naked dance parties and pornography viewing, Seibel sexually abused students after locking the doors to a classroom adjacent to the basketball gym. He held his group masturbation sessions and so-called penis enlargement and measuring sessions on campus, and was finally caught in 2003 with child pornography on his computer.

Despite reports of inappropriate behavior made to another teacher in the fall of 2000, who in turn reported Seibel to two administrators, nothing was reported to law enforcement and Seibel remained at the school for another three years.

Since Seibel’s arrest in Minnesota, multiple survivors have come forward alleging abuse by Seibel during his 11-year career with the school. Seibel also was convicted in Los Angeles of soliciting or engaging in lewd conduct in a public place.